Discovery of a radio halo (and relic) in a $M_{500} < 2 \times 10^{14}$ M$_\odot$ cluster
| Autor: | Botteon, A., Cassano, R., van Weeren, R. J., Shimwell, T. W., Bonafede, A., Br��ggen, M., Brunetti, G., Cuciti, V., Dallacasa, D., de Gasperin, F., Di Gennaro, G., Gastaldello, F., Hoang, D. N., Rossetti, M., R��ttgering, H. J. A. |
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| Rok vydání: | 2021 |
| Předmět: |
High Energy Astrophysical Phenomena (astro-ph.HE)
Cosmology and Nongalactic Astrophysics (astro-ph.CO) Astrophysics::High Energy Astrophysical Phenomena Astrophysics of Galaxies (astro-ph.GA) FOS: Physical sciences Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics::Galaxy Astrophysics |
| DOI: | 10.48550/arxiv.2105.14025 |
| Popis: | Radio halos are diffuse synchrotron sources observed in dynamically unrelaxed galaxy clusters. Current observations and models suggest that halos trace turbulent regions in the intra-cluster medium where mildly relativistic particles are re-accelerated during cluster mergers. Due to the higher luminosities and detection rates with increasing cluster mass, radio halos have been mainly observed in massive systems ($M_{500} \gtrsim 5 \times10^{14}$ M$_\odot$). Here, we report the discovery of a radio halo with a largest linear scale of $\simeq$750 kpc in PSZ2G145.92-12.53 ($z=0.03$) using LOFAR observations at 120$-$168 MHz. With a mass of $M_{500} = (1.9\pm0.2) \times 10^{14}$ M$_\odot$ and a radio power at 150 MHz of $P_{150} = (3.5 \pm 0.7) \times 10^{23}$ W/Hz, this is the least powerful radio halo in the least massive cluster discovered to date. Additionally, we discover a radio relic with a mildly convex morphology at $\sim$1.7 Mpc from the cluster center. Our results demonstrate that LOFAR has the potential to detect radio halos even in low-mass clusters, where the expectation to form them is very low ($\sim$5%) based on turbulent re-acceleration models. Together with the observation of large samples of clusters, this opens the possibility to constrain the low end of the power-mass relation of radio halos. 8 pages, 5 figures, 1 table (including appendix). Accepted for publication in ApJL |
| Databáze: | OpenAIRE |
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